Master of Flutter lifecycle / Flutter Kaigi 2023

""LJSB Master of Flutter lifecycle @_a_akira AAkira Flutter Kaigi 2023

% About me 2 M3, Inc. Akira Aratani https://aakira.app https://aakira.studio
🐕 ✈ 📷 🎾 🤸 🚁⊿ aakira.studio _a_akira AAkira chai_cavachon

% M3, Inc. 3 https://www.m3tech.blog/ https://jobs.m3.com/engineer/ m3_engineering m3techchannel160 https://jobs.m3.com/product/ エンジニアリングの力で医療の世界を変えていく
The Power of Medical Innovation

% M3, Inc. 4 https://www.m3tech.blog/ https://jobs.m3.com/engineer/ m3_engineering m3techchannel160 https://jobs.m3.com/product/ エンジニアリングの力で医療の世界を変えていく
The Power of Medical Innovation Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% • Flutter Lifecycle • Widget Lifecycle • App Lifecycle
• Navigation & Routing • Handling Flutter lifecycle • Summary 5 Agenda

% • Flutter Lifecycle • Widget Lifecycle • App Lifecycle
• Navigation & Routing • Handling Flutter lifecycle • Summary 6 Agenda 目的 Flutterのライフサイクルの仕組みを知って、必要になった時に適切にイベントハンドリングできるようになる。 OK CANCEL

% Lifecycleとは？ 7

% 8 https://developer.android.com/guide/components/activities/activity-lifecycle https://developer.apple.com/documentation/uikit/uiviewcontroller

% • ライフサイクルは主に2つある • Widget自体のライフサイクル • アプリ全体のライフサイクル 9 Flutter lifecycle

% • ライフサイクルは主に2つある • Widget自体のライフサイクル • アプリ全体のライフサイクル • OSに依るもの •
画面遷移に依るもの 10 Flutter lifecycle

% • ライフサイクルは主に2つある • Widget自体のライフサイクル → 主にStateful Widget • アプリ全体のライフサイクル
• OSに依るもの → WidgetBindingObserver • 画面遷移に依るもの → NavigatorObserver 11 Flutter lifecycle

• OSに依るもの → WidgetBindingObserver • 画面遷移に依るもの → NavigatorObserver 12 Flutter lifecycle Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

• OSに依るもの → WidgetBindingObserver • 画面遷移に依るもの → NavigatorObserver 13 Flutter lifecycle Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

• OSに依るもの → WidgetBindingObserver • 画面遷移に依るもの → NavigatorObserver X Flutter lifecycle Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% • StatelessWidget • StatefulWidget • ProxyWidget(InheritedWidget, ParentDataWidget) • RenderObjectWidget
14 Widget

15 Widget

16 Widget

% • 状態を持つことを目的としたWidget • 状態があるView componentが多く利用している • Image, Button, Radio,
DropDownMenu, Slider, Chip... 17 Stateful Widget

% • _StateLifecycle • created • initialized • ready •
defunct 18 State lifecycle

% 19 State lifecycle 初期値、Stateオブジェクトが生成された後 Stateオブジェクトはまだない Stateオブジェクトが利用可能 Stateオブジェクトは利用不可 • _StateLifecycle
• created • initialized • ready • defunct

% • createState • initState • didChangeDependencies • build •
didUpdateWidget • setState • deactivate • dispose 20 Stateful Widgetで重要なライフサイクルのイベント

% • createState • initState • didChangeDependencies • build •
didUpdateWidget • setState • deactivate • dispose 21 Stateful Widgetで重要なライフサイクルのイベント createState initState didChangeDependencies deactivate dispose defunct ready created build didUpdateWidget setState initialized

% createState initState didChangeDependencies deactivate dispose defunct ready created build
didUpdateWidget setState initialized 22

didUpdateWidget setState initialized build 26 setState didUpdateWidget

didUpdateWidget setState initialized deactivate 27 dispose

% • Flutterの描画にはWidget treeとElement tree, RenderObject treeがある • Elementにもライフサイクルが存在する(_ElementLifecycle) •
initial • active • inactive • defunct 28 Element lifecycle

% 実際の挙動 29

% @override Widget build(BuildContext context) { return Container( padding: const
EdgeInsets.all(32), decoration: BoxDecoration( color: const Color(0xffd8e2ff), borderRadius: BorderRadius.circular(32), ), child: Column( mainAxisSize: MainAxisSize.min, children: [ Text('Parent counter: $_counter'), const SizedBox(height: 8), OutlinedButton( onPressed: () => _incrementCounter(), child: const Text('Increment parent'), ), const SizedBox(height: 32), ChildWidget(), ], ), ); } 30 親Widet

EdgeInsets.all(32), decoration: BoxDecoration( color: const Color(0xfffdd7fa), borderRadius: BorderRadius.circular(32), ), child: Column( children: [ Text('Child counter: $_counter'), const SizedBox(height: 8), OutlinedButton( onPressed: () => _incrementCounter(), child: const Text('Increment child'), ), ], ), ); } 34 子Widet

% 35 Child counter: 0 Parent counter: 0 Increment parent
Increment child

% parent: initState parent: didChangeDependencies parent: build child: initState child:
didChangeDependencies child: build 初回ビルド時 Child counter: 0 Parent counter: 0 Increment parent Increment child 36

% child: setState child: build Childボタン押下時 Child counter: 5 Parent
counter: 0 Increment parent Increment child 37

% Parentボタン押下時 Child counter: 5 Parent counter: 3 Increment parent
Increment child parent: setState parent: build child: didUpdateWidget child: build 38

Increment child parent: setState parent: build child: didUpdateWidget child: build 親のWidgetが更新されたため呼ばれる 39

% parent: deactivate child: deactivate child: dispose parent: dispose Widget破棄時
Child counter: 5 Parent counter: 3 Increment parent Increment child 40

% 41 didUpdateWidget呼ばれないようにする

Increment child parent: setState parent: build child: didUpdateWidget child: build 42 子も更新されてしまう

% ), child: Column( mainAxisSize: MainAxisSize.min, children: [ Text('Parent counter:
$_count const SizedBox(height: 8), OutlinedButton( onPressed: () => _increment child: const Text('Incremen ), const SizedBox(height: 32), const ChildWidget(), ], ), ); } 44

Increment child parent: setState parent: build 親のみRebuildされる 45

Increment child parent: setState parent: build 親のみRebuildされる 46 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

Increment child parent: setState parent: build 親のみRebuildされる 47 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

Increment child parent: setState parent: build 親のみRebuildされる X Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% • OSによる操作をFlutterのフレームワークが吸収したもの • Flutter 3.13.0で大きな変更があった • 状態の追加(hidden) • イベントの発火パターンが増えた
• 状態遷移の流れが変わった • AppLifecycleListener(WidgetBindingObserver)でハンドリング 48 App lifecycle

% • resumed • inactive • hidden • paused •
detached 49 App lifecycle state

% • resumed • inactive • hidden → Flutter 3.13.0から追加
• paused • detached 50 App lifecycle state https://docs. fl utter.dev/release/breaking-changes/add-applifecyclestate-hidden

% 51 https://github.com/ fl utter/engine/pull/40542

% 52 https://github.com/ fl utter/engine/pull/40542 hidden 3.13.0以前は非対応だった macOSとLinuxのために追加された OK
CANCEL

% 53 App Lifecycleの状態遷移図 resumed inactive hidden paused detached onInactive
onHide onPause onDetach onResume onShow onRestart

% 54 App Lifecycleの状態遷移図 resumed inactive hidden paused detached onInactive
onHide onPause onDetach onResume onShow onRestart Foreground状態 Kill状態 Background状態 --------------------- ---------------------

% • ライフサイクルイベント発火パターンが3.13.0の前後で異なる • OSによってイベント、発火タイミングが異なる 55 実際の挙動

% • アプリからOSホームへの遷移 • OSホームからアプリへの遷移 • アプリからタスク一覧への遷移 • タスク一覧からアプリへの遷移 •
画面OFF • 画面ON • アプリ終了 56 実際の挙動 • Noti fi cation, Control Centerを表示 • Noti fi cation, Control Centerを非表示 • 画面分割 • 画面分割時のフォーカス切り替え • 自分のアプリ側の画面分割を終了 • もう一方のアプリ側の画面分割を終了

% ~3.13.0 inactive paused アプリからOSホームへの遷移 57 3.13.0~ inactive hidden paused
J04

% ~3.13.0 resumed OSホームからアプリへの遷移 58 3.13.0~ hidden inactive resumed J04

% ~3.13.0 inactive paused (その後OSホーム、他アプリにいっても変化なし) アプリからタスク一覧への遷移 59 3.13.0~ inactive hidden
paused (その後OSホーム、他アプリにいっても変化なし)

% ~3.13.0 inactive (その後OSホーム、他アプリに遷移した場合) paused アプリからタスク一覧への遷移 60 3.13.0~ inactive (その後OSホーム、他アプリに遷移した場合)
hidden paused J04

% ~3.13.0 resumed タスク一覧からアプリへの遷移 61 3.13.0~ hidden inactive resumed

% ~3.13.0 • アプリ=>タスク一覧=>アプリ resumed • OSホーム=>タスク一覧=>アプリ inactive resumed タスク一覧からアプリへの遷移
62 3.13.0~ • アプリ=>タスク一覧=>アプリ resumed • OSホーム=>タスク一覧=>アプリ hidden inactive resumed J04

% ~3.13.0 inactive paused 画面OFF 63 3.13.0~ inactive hidden paused
J04

% ~3.13.0 resumed 画面ON 64 3.13.0~ hidden inactive resumed J04

% ~3.13.0 イベントなし通知欄を表示 65 3.13.0~ inactive

% ~3.13.0 イベントなし通知欄を非表示 66 3.13.0~ resumed

% ~3.13.0 • 開く inactive • 閉じる resumed 通知欄, 設定
67 3.13.0~ • 開く inactive • 閉じる resumed J04

% ~3.13.0 inactive paused detached アプリ終了 68 3.13.0~ inactive hidden
paused detached J04

% ~3.13.0 (inactive) (paused) resumed inactive resumed 画面分割 (Android) 69
3.13.0~ (inactive) (hidden) (paused) hidden inactive resumed

% ~3.13.0 inactive resumed 画面分割 (iPad) 70 3.13.0~ inactive resumed
J1BE

% ~3.13.0 変化なし画面分割時のフォーカス切り替え 71 3.13.0~ • unfocused inactive •
focused resumed

% ~3.13.0 (変化なし) 画面分割時のフォーカス切り替え 72 3.13.0~ (変化なし) J1BE

% ~3.13.0 inactive paused 自分のアプリ側の画面分割を終了 73 3.13.0~ inactive hidden paused

% ~3.13.0 inactive paused 自分のアプリ側の画面分割を終了 74 3.13.0~ inactive hidden paused
J1BE

% ~3.13.0 フォーカスに関係なく変化なしもう一方のアプリ側の画面分割を終了 75 3.13.0~ • unfocused resumed •
focused 変化なし

% ~3.13.0 inactive resumed もう一方のアプリ側の画面分割を終了 76 3.13.0~ inactive resumed J1BE

% 3.13.0~ • Focus resumed • Unfocus inactive フォーカス切り替え 77
NBD04

% 3.13.0~ • 覆う hidden • 表示 inactive 画面を覆う 78
NBD04

% 3.13.0~ • 画面OFF inactive hidden • 画面ON inactive resumed
画面ON/OFF 79 NBD04

% 3.13.0~ inactive hidden 最小化 80 NBD04

% 3.13.0~ inactive resumed 最小化からフォーカス 81 NBD04

% 3.13.0~ inactive hidden inactive resumed inactive ... (何度かイベント発火) resumed
フルスクリーン化 82 NBD04

% 3.13.0~ inactive hidden inactive resumed inactive hidden inactive resumed
フルスクリーン解除 83 NBD04

% ~3.13.0 イベントなし WEB 84 3.13.0~ イベントなし

% 85 Android iOS(iPhone/iPad) アプリからOSホームへの遷移 inactive->hidden->paused inactive->hidden->paused OSホームからアプリへの遷移 hid->ina->res hid->ina->res
アプリからタスク一覧への遷移 ina->hid->pau ina, (to home: hid->pau) タスク一覧からアプリへの遷移 hid->ina->res res, (from home: hid->ina->res) 画面OFF ina->hid->pau ina->hid->pau 画面ON hid->ina->res hid->ina->res Noti fi cation, Control Centerを表示 inactive inactive Noti fi cation, Control Centerを非表示 resumed resumed アプリ終了 ina->hid->pau->detached ina->hid->pau->detached 画面分割 hid->ina->res ina->res 画面分割時のフォーカス切り替え inactive/resumed - 自分のアプリ側の画面分割を終了 ina->hid->pau ina->hid->pau もう一方のアプリ側の画面分割を終了 focused: -, unfocused: resumed ina->res

% 86 Android iOS(iPhone/iPad) アプリからOSホームへの遷移 inactive->hidden->paused inactive->hidden->paused OSホームからアプリへの遷移 hid->ina->res hid->ina->res
アプリからタスク一覧への遷移 ina->hid->pau ina, (to home: hid->pau) タスク一覧からアプリへの遷移 hid->ina->res res, (from home: hid->ina->res) 画面OFF ina->hid->pau ina->hid->pau 画面ON hid->ina->res hid->ina->res Noti fi cation, Control Centerを表示 inactive inactive Noti fi cation, Control Centerを非表示 resumed resumed アプリ終了 ina->hid->pau->detached ina->hid->pau->detached 画面分割 hid->ina->res ina->res 画面分割時のフォーカス切り替え inactive/resumed - 自分のアプリ側の画面分割を終了 ina->hid->pau ina->hid->pau もう一方のアプリ側の画面分割を終了 focused: -, unfocused: resumed ina->res

% • 今まではWidgetsBindingObserverをWidgetに対して実装する必要があった • 3.13.0からAppLifecycleListenerが追加 87 AppLifecycleListener

% 88 class ExamplePage extends StatefulWidget { const ExamplePage({super.key}); @override
State<ExamplePage> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with WidgetsBindingObserver { @override void initState() { super.initState(); WidgetsBinding.instance.addObserver(this); } @override void dispose() { WidgetsBinding.instance.removeObserver(this); super.dispose(); } @override void didChangeAppLifecycleState(AppLifecycleState state) { print(state); } @override Widget build(BuildContext context) { return Contaienr(); } } WidgetsBindingObserver

% 89 const ExamplePage({super.key}); @override State<ExamplePage> createState() => _ExamplePageState(); }
class _ExamplePageState extends State<ExamplePage> with WidgetsBindingObserver { @override void initState() { super.initState(); WidgetsBinding.instance.addObserver(this); } @override void dispose() { WidgetsBinding.instance.removeObserver(this); super.dispose(); } @override void didChangeAppLifecycleState(AppLifecycleState state) { print(state); } @override Widget build(BuildContext context) { return Contaienr();

State<ExamplePage> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> { late final AppLifecycleListener appLifecycleListener; @override void initState() { super.initState(); appLifecycleListener = AppLifecycleListener( onShow: () => print('onShow'), onResume: () => print('onResume'), onHide: () => print('onHide'), onInactive: () => print('onInactive'), onPause: () => print('onPause'), onDetach: () => print('onDetach'), onRestart: () => print('onRestart'), onStateChange: (state) => print(state.toString()), ); } @override void dispose() { appLifecycleListener.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return Container(); } } AppLifecycleListener

State<ExamplePage> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> { late final AppLifecycleListener appLifecycleListener; @override void initState() { super.initState(); appLifecycleListener = AppLifecycleListener( onShow: () => print('onShow'), onResume: () => print('onResume'), onHide: () => print('onHide'), onInactive: () => print('onInactive'), onPause: () => print('onPause'), onDetach: () => print('onDetach'), onRestart: () => print('onRestart'), onStateChange: (state) => print(state.toString()), ); }

State<ExamplePage> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> { late final AppLifecycleListener appLifecycleListener; @override void initState() { super.initState(); appLifecycleListener = AppLifecycleListener( onStateChange: (state) => print(state.toString()), ); } @override void dispose() { appLifecycleListener.dispose(); super.dispose(); } @override

% 97 void initState() { super.initState(); appLifecycleListener = AppLifecycleListener( onShow:
() => print('onShow'), onResume: () => print('onResume'), onHide: () => print('onHide'), onInactive: () => print('onInactive'), onPause: () => print('onPause'), onDetach: () => print('onDetach'), onRestart: () => print('onRestart'), onStateChange: (state) => print(state.toString()), ); } @override void dispose() { appLifecycleListener.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return Container(); } }

% 98 @override State<ExamplePage> createState() => _ExamplePageState(); } class _ExamplePageState
extends State<ExamplePage> { late final AppLifecycleListener appLifecycleListener; @override void initState() { super.initState(); appLifecycleListener = AppLifecycleListener( onShow: () => print('onShow'), onResume: () => print('onResume'), onHide: () => print('onHide'), onInactive: () => print('onInactive'), onPause: () => print('onPause'), onDetach: () => print('onDetach'), onRestart: () => print('onRestart'), onStateChange: (state) => print(state.toString()), ); } @override void dispose() { appLifecycleListener.dispose(); super.dispose(); } AppLifecycleStateにはない

% AppLifecycleState inactive hidden paused アプリからOSホームへの遷移 99 AppLifecycleListener onInactive onHide
onPause AppLifecycleState AppLifecycleListener onRestart onShow onResume hidden inactive resumed OSホームからアプリへの遷移

% AppLifecycleState inactive hidden paused アプリからOSホームへの遷移 100 onInactive onHide onPause
AppLifecycleState onRestart onShow onResume hidden inactive resumed OSホームからアプリへの遷移 AppLifecycleListener AppLifecycleListener

% 101 inactive hidden paused アプリからOSホームへの遷移 AppLifecycleState onInactive onHide onPause
AppLifecycleState onRestart onShow onResume AppLifecycleListener AppLifecycleListener hidden inactive resumed OSホームからアプリへの遷移 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% 102 inactive hidden paused アプリからOSホームへの遷移 AppLifecycleState AppLifecycleListener AppLifecycleListener onInactive
onHide onPause AppLifecycleState onRestart onShow onResume hidden inactive resumed OSホームからアプリへの遷移 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% X inactive hidden paused アプリからOSホームへの遷移 AppLifecycleState AppLifecycleListener AppLifecycleListener onInactive
onHide onPause AppLifecycleState onRestart onShow onResume hidden inactive resumed OSホームからアプリへの遷移 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% • Widgetごとのライフサイクルハンドリング • アプリ全体のライフサイクルハンドリング • 画面遷移はハンドリングできない => Navigator history
stackを監視する必要がある 103 ここまででできること

% • 現在主流のものは主に3パターン • Navigator (通称Navigator1.0) • Router (通称Navigator2.0) •
ライブラリーを使う(サードパーティ含む) • fl utter.dev/go_router • codeness.ly/auto_route • tom.gilder.dev/routemaster • etc... 104 Navigator

% • 現在主流のものは主に3パターン • Navigator (通称Navigator1.0) • Router (通称Navigator2.0) •
ライブラリーを使う(サードパーティ含む) • fl utter.dev/go_router • codeness.ly/auto_route • tom.gilder.dev/routemaster • etc... 105 Navigator https://docs. fl utter.dev/ui/navigation

% 106 Page1 Page2 Page3 Page1 Page2 Page3 Page4 Page1
Page2 Page3 Push Page4 Pop Page4

% 107 Page1 Page2 Page3 Page1 Page2 Page3 Page4 Page1
Page2 Page3 Navigator Router (GoRouter etc...) Widget

% • Navigator history stackの変化を監視 • didPush • didPop •
didRemove • didReplace • (didStartUserGesture) • (didStopUserGesture) 108 NavigatorObserver

% 109 class NavigatorObserver { NavigatorState? get navigator => _navigators[this];
static final Expando<NavigatorState> _navigators = Expando<NavigatorState>(); void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) { } void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { } void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { } void didReplace({ Route<dynamic>? newRoute, Route<dynamic>? oldRoute }) { } void didStartUserGesture(Route<dynamic> route, Route<dynamic>? previousRoute) { } void didStopUserGesture() { } }

% • RouteObserverと組み合わせて利用する • 実装されたWidgetのNavigationに変更があると通知される • didPopNext • didPush •
didPop • didPushNext 110 RouteAware

% 111 abstract mixin class RouteAware { void didPopNext() {
} void didPush() { } void didPop() { } void didPushNext() { } }

} void didPush() { } void didPop() { } void didPushNext() { } } Page1 Page2 対象WidgetがPushされたタイミング

} void didPush() { } void didPop() { } void didPushNext() { } } 対象Widgetの上に別のWidgetが Pushされたタイミング Page1 Page2 Page3

} void didPush() { } void didPop() { } void didPushNext() { } } 対象Widgetの上にある別のWidgetが Popされたタイミング Page1 Page2 Page3

} void didPush() { } void didPop() { } void didPushNext() { } } 対象WidgetがPopされたタイミング Page1 Page2

% 116 class RouteObserver<R extends Route<dynamic>> extends NavigatorObserver { @override
void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { ... } @override void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) { ... } ... }

% 117 final RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>();

% 118 final RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>(); Navigator( pages: [
... ], onPopPage: (route, result) { ... } ); MaterialApp( routes: <String, WidgetBuilder>{ ... }, ); GoRouter( initialLocation: '/', routes: [ ... ], ); Navigator1.0 Navigator2.0(Router) GoRouter

% 119 final RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>(); Navigator( observers: [
routeObserver, ], pages: [ ... ], onPopPage: (route, result) { ... } ); MaterialApp( navigatorObservers: [ routeObserver, ], routes: <String, WidgetBuilder>{ ... }, ); GoRouter( observers: [ routeObserver, ], initialLocation: '/', routes: [ ... ], ); Navigator1.0 GoRouter Navigator2.0(Router)

% 120 class ExamplePage extends StatefulWidget { const ExamplePage({ super.key
}); @override State<StatefulWidget> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with RouteAware { @override void didChangeDependencies() { super.didChangeDependencies(); routeObserver.subscribe( this, ModalRoute.of(context)! as PageRoute<dynamic>, ); } @override void dispose() { routeObserver.unsubscribe(this); super.dispose(); } @override void didPush() { } @override void didPop() { } @override void didPushNext() { } @override void didPopNext() { } @override Widget build(BuildContext context) { return Container(); } }

% class ExamplePage extends StatefulWidget { const ExamplePage({ super.key });
@override State<StatefulWidget> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with RouteAware { @override void didChangeDependencies() { super.didChangeDependencies(); routeObserver.subscribe( this, ModalRoute.of(context)! as PageRoute<dynamic>, ); } @override 121 @override void didPush() } @override void didPop() } @override void didPushNe } @override void didPopNex } @override Widget build(B return Conta } }

% 122 void didPush() } @override void didPop() } @override
void didPushNe } @override void didPopNex } @override Widget build(B return Conta } } const ExamplePage({ super.key }); @override State<StatefulWidget> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with RouteAware { @override void didChangeDependencies() { super.didChangeDependencies(); routeObserver.subscribe( this, ModalRoute.of(context)! as PageRoute<dynamic>, ); } @override void dispose() { routeObserver.unsubscribe(this); super.dispose(); }

% 123 @override void didPush() { } @override void didPop()
{ } @override void didPushNext() { } @override void didPopNext() { } @override Widget build(BuildContext context) { return Container(); } } extends StatefulWidget { e({ super.key }); dget> createState() => _ExamplePageState(); State extends State<ExamplePage> with RouteAware { pendencies() { eDependencies(); subscribe( f(context)! as PageRoute<dynamic>,

% 124 void didPush() } @override void didPop() } @override
void didPushNe } @override void didPopNex } @override Widget build(B return Conta } } const ExamplePage({ super.key }); @override State<StatefulWidget> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with RouteAware { @override void didChangeDependencies() { super.didChangeDependencies(); routeObserver.subscribe( this, ModalRoute.of(context)! as PageRoute<dynamic>, ); } @override void dispose() { routeObserver.unsubscribe(this); super.dispose(); }

% void didPush() } @override void didPop() } @override void
didPushNe } @override void didPopNex } @override Widget build(B return Conta } } const ExamplePage({ super.key }); @override State<StatefulWidget> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with RouteAware { @override void didChangeDependencies() { super.didChangeDependencies(); routeObserver.subscribe( this, ModalRoute.of(context)! as PageRoute<dynamic>, ); } @override void dispose() { routeObserver.unsubscribe(this); super.dispose(); } 125 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

didPushNe } @override void didPopNex } @override Widget build(B return Conta } } const ExamplePage({ super.key }); @override State<StatefulWidget> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with RouteAware { @override void didChangeDependencies() { super.didChangeDependencies(); routeObserver.subscribe( this, ModalRoute.of(context)! as PageRoute<dynamic>, ); } @override void dispose() { routeObserver.unsubscribe(this); super.dispose(); } 126 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

didPushNe } @override void didPopNex } @override Widget build(B return Conta } } const ExamplePage({ super.key }); @override State<StatefulWidget> createState() => _ExamplePageState(); } class _ExamplePageState extends State<ExamplePage> with RouteAware { @override void didChangeDependencies() { super.didChangeDependencies(); routeObserver.subscribe( this, ModalRoute.of(context)! as PageRoute<dynamic>, ); } @override void dispose() { routeObserver.unsubscribe(this); super.dispose(); } X Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% 127 Handling Flutter lifecycle • 従来のAndroid, iOSのようなライフサイクルイベントは Flutterには用意されていない •
Android: onResume, onPause, etc. iOS: viewDidAppear, viewDidDesappear, etc. • 画面遷移 • 端末の画面ON/OFF • アプリ自体のバックグラウンドへの移行イベント

% 128 Handling Flutter lifecycle • 従来のAndroid, iOSのようなライフサイクルイベントは Flutterには用意されていない •
Android: onResume, onPause, etc. iOS: viewDidAppear, viewDidDesappear, etc. • 画面遷移 • 端末の画面ON/OFF • アプリ自体のバックグラウンドへの移行イベント Handling lifecycle AppLifecycleListener (WidgetBindingObserver)と NavigationObserverを組み合わせる必要がある OK CANCEL

% 129 sealed class LifecycleEvent { const LifecycleEvent(this.isSystemEvent); final bool
isSystemEvent; } class LifecycleEventResumed extends LifecycleEvent { const LifecycleEventResumed(super.isSystemEvent); @override String toString() => 'LifecycleEventResumed(isSystemEvent: $isSystemEvent)'; } class LifecycleEventPaused extends LifecycleEvent { const LifecycleEventPaused(super.isSystemEvent); @override String toString() => 'LifecycleEventPaused(isSystemEvent: $isSystemEvent)'; } typedef LifecycleObserverCallback = void Function(LifecycleEvent event);

isSystemEvent; } class LifecycleEventResumed extends LifecycleEvent { const LifecycleEventResumed(super.isSystemEvent); @override String toString() => 'LifecycleEventResumed(isSystemEvent: $isSystemEvent)'; } class LifecycleEventPaused extends LifecycleEvent { const LifecycleEventPaused(super.isSystemEvent); @override String toString() => 'LifecycleEventPaused(isSystemEvent: $isSystemEvent)'; }

isSystemEvent; } class LifecycleEventResumed extends LifecycleEvent { const LifecycleEventResumed(super.isSystemEvent); @override String toString() => 'LifecycleEventResumed(isSystemEvent: $isSystemEvent)'; } class LifecycleEventPaused extends LifecycleEvent { const LifecycleEventPaused(super.isSystemEvent); @override String toString() => 'LifecycleEventPaused(isSystemEvent: $isSystemEvent)'; } Navigation or 画面ON, OFFなどのイベントを判別するため

% 132 final bool isSystemEvent; } class LifecycleEventResumed extends LifecycleEvent
{ const LifecycleEventResumed(super.isSystemEvent); @override String toString() => 'LifecycleEventResumed(isSystemEvent: $isSystemEvent)'; } class LifecycleEventPaused extends LifecycleEvent { const LifecycleEventPaused(super.isSystemEvent); @override String toString() => 'LifecycleEventPaused(isSystemEvent: $isSystemEvent)'; } typedef LifecycleObserverCallback = void Function(LifecycleEvent event);

% 133 class AppLifecycleObserver with RouteAware { AppLifecycleObserver({ required this.routeObserver,
required ModalRoute<dynamic> route, required this.callback, }) { _appLifecycleListener = AppLifecycleListener( onResume: () { callback(const LifecycleEventResumed(true)); }, onPause: () { callback(const LifecycleEventPaused(true)); }, ); routeObserver.subscribe(this, route); } late final AppLifecycleListener _appLifecycleListener; final RouteObserver routeObserver; final LifecycleObserverCallback callback; @override void didPush() { callback(const LifecycleEventResumed(false)); } @override void didPop() { callback(const LifecycleEventPaused(false)); _appLifecycleListener.dispose(); } @override void didPushNext() { callback(const LifecycleEventPaused(false)); } @override void didPopNext() { callback(const LifecycleEventResumed(false)); } }

% 134 class AppLifecycleObserver with RouteAware { AppLifecycleObserver({ required this.routeObserver,
required ModalRoute<dynamic> route, required this.callback, }) { _appLifecycleListener = AppLifecycleListener( onResume: () { callback(const LifecycleEventResumed(true)); }, onPause: () { callback(const LifecycleEventPaused(true)); }, ); routeObserver.subscribe(this, route); } late final AppLifecycleListener _appLifecycleListener; final RouteObserver routeObserver; final LifecycleObserverCallback callback; @override void didPush() {

% class AppLifecycleObserver with RouteAware { AppLifecycleObserver({ required this.routeObserver, required
ModalRoute<dynamic> route, required this.callback, }) { _appLifecycleListener = AppLifecycleListener( onResume: () { callback(const LifecycleEventResumed(true)); }, onPause: () { callback(const LifecycleEventPaused(true)); }, ); routeObserver.subscribe(this, route); } late final AppLifecycleListener _appLifecycleListener; final RouteObserver routeObserver; final LifecycleObserverCallback callback; @override void didPush() { 135

% 139 late final AppLifecycleListener _appLifecycleListener; final RouteObserver routeObserver; final
LifecycleObserverCallback callback; @override void didPush() { callback(const LifecycleEventResumed(false)); } @override void didPop() { callback(const LifecycleEventPaused(false)); _appLifecycleListener.dispose(); } @override void didPushNext() { callback(const LifecycleEventPaused(false)); } @override void didPopNext() { callback(const LifecycleEventResumed(false)); } }

% late final AppLifecycleListener _appLifecycleListener; final RouteObserver routeObserver; final LifecycleObserverCallback
callback; @override void didPush() { callback(const LifecycleEventResumed(false)); } @override void didPop() { callback(const LifecycleEventPaused(false)); _appLifecycleListener.dispose(); } @override void didPushNext() { callback(const LifecycleEventPaused(false)); } @override void didPopNext() { callback(const LifecycleEventResumed(false)); } } 140

% 141 final RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>(); Navigator( observers: [
routeObserver, ], pages: [ ... ], onPopPage: (route, result) { ... } ); MaterialApp( navigatorObservers: [ routeObserver, ], routes: <String, WidgetBuilder>{ ... }, ); GoRouter( observers: [ routeObserver, ], initialLocation: '/', routes: [ ... ], ); Navigator1.0 GoRouter Navigator2.0(Router) 利用側

% 142 利用側 class Page extends StatefulWidget { const Page({super.key});
@override State<StatefulWidget> createState() => _PageState(); } class _PageState extends State<Page> { bool _initialized = false; @override void didChangeDependencies() { super.didChangeDependencies(); if(!_initialized) { AppLifecycleObserver( routeObserver: routeObserver, route: ModalRoute.of(context)!, callback: (event) { }, ); _initialized = true; } } @override Widget build(BuildContext context) { return Container(); } }

% 143 t { ate() => eState(); class _PageState extends
State<Page> { bool _initialized = false; @override void didChangeDependencies() { super.didChangeDependencies(); if(!_initialized) { AppLifecycleObserver( routeObserver: routeObserver, route: ModalRoute.of(context)!, callback: (event) { }, ); _initialized = true; } }

% 144 t { ate() => eState(); class _PageState extends
State<Page> { bool _initialized = false; @override void didChangeDependencies() { super.didChangeDependencies(); if(!_initialized) { AppLifecycleObserver( routeObserver: routeObserver, route: ModalRoute.of(context)!, callback: (event) { }, ); _initialized = true; } }

% • 問題点 • 各Widgetでそれぞれ書くのは冗長 • Contextが必要 145 Handling Flutter
lifecycle

lifecycle PageName(String)をKeyにしたLifecycleObserverを作ってみる

lifecycle PageName(String)をKeyにしたLifecycleObserverを作ってみる自作LifecycleObserverは参考程度に

% 148 class AppLifecycleObserver extends NavigatorObserver { AppLifecycleObserver() { _appLifecycleListener
= AppLifecycleListener( onResume: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(true)); }, onPause: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventPaused(true)); }, ); } late final AppLifecycleListener _appLifecycleListener; final Map<String, Set<LifecycleObserverCallback>> _subscribers = <String, Set<LifecycleObserverCallback>>{}; final List<Route<dynamic>> _routeStack = []; @override void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.remove(route); _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } @override void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.add(route); _emitLifecycleEvent(previousRoute, const LifecycleEventPaused(false)); _emitLifecycleEvent(route, const LifecycleEventResumed(false)); } @override void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { if (_routeStack.last == route) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } _routeStack.remove(route); } @override void didReplace({Route<dynamic>? newRoute, Route<dynamic>? oldRoute}) { final index = _routeStack.indexWhere((element) => element == oldRoute); if (_routeStack.last == oldRoute) { _emitLifecycleEvent(oldRoute, const LifecycleEventPaused(false)); } _routeStack.remove(oldRoute); if (index >= 0 && newRoute != null) { _routeStack.insert(index, newRoute); } if (_routeStack.last == newRoute) { _emitLifecycleEvent(newRoute, const LifecycleEventResumed(false)); } } void dispose() { _appLifecycleListener.dispose(); _subscribers.clear(); } void subscribe(String key, LifecycleObserverCallback callback) { final Set<LifecycleObserverCallback> subscribers = _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback); if (_routeStack.isNotEmpty && _routeStack.last.settings.name == key) { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(false)); } } void unsubscribe(String key) { _subscribers.remove(key); } void _emitLifecycleEvent(Route<dynamic>? route, LifecycleEvent event) { final key = route?.settings.name; if (key == null) { return; } final subscribers = _subscribers[key]; if (subscribers == null) { return; } for (final subscriber in subscribers) { subscriber.call(event); } } }

= AppLifecycleListener( onResume: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(true)); }, onPause: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventPaused(true)); }, ); } late final AppLifecycleListener _appLifecycleListener; final Map<String, Set<LifecycleObserverCallback>> _subscribers = <String, Set<LifecycleObserverCallback>>{}; final List<Route<dynamic>> _routeStack = []; @override void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.remove(route); @over void fin if _ } _ro if _ } if _ } } void _ap _su } void fin

= AppLifecycleListener( onResume: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(true)); }, onPause: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventPaused(true)); }, ); } late final AppLifecycleListener _appLifecycleListener; final Map<String, Set<LifecycleObserverCallback>> _subscribers = <String, Set<LifecycleObserverCallback>>{}; final List<Route<dynamic>> _routeStack = []; @override void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.remove(route); @over void fin if _ } _ro if _ } if _ } } void _ap _su } void fin Navigation stack historyを管理

= AppLifecycleListener( onResume: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(true)); }, onPause: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventPaused(true)); }, ); } late final AppLifecycleListener _appLifecycleListener; final Map<String, Set<LifecycleObserverCallback>> _subscribers = <String, Set<LifecycleObserverCallback>>{}; final List<Route<dynamic>> _routeStack = []; @override void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.remove(route); @over void fin if _ } _ro if _ } if _ } } void _ap _su } void fin StringのKeyでListenerの管理 Keyには route.nameを使う

= AppLifecycleListener( onResume: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(true)); }, onPause: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventPaused(true)); }, ); } late final AppLifecycleListener _appLifecycleListener; final Map<String, Set<LifecycleObserverCallback>> _subscribers = <String, Set<LifecycleObserverCallback>>{}; final List<Route<dynamic>> _routeStack = []; @override void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.remove(route); @over void fin if _ } _ro if _ } if _ } } void _ap _su } void fin AppLifecycleListenerは同じ

= AppLifecycleListener( onResume: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(true)); }, onPause: () { _emitLifecycleEvent(_routeStack.last, const LifecycleEventPaused(true)); }, ); } late final AppLifecycleListener _appLifecycleListener; final Map<String, Set<LifecycleObserverCallback>> _subscribers = <String, Set<LifecycleObserverCallback>>{}; final List<Route<dynamic>> _routeStack = []; @override void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.remove(route); @over void fin if _ } _ro if _ } if _ } } void _ap _su } void fin Navigation route の一番上にあるRouteに通知

% 154 e)); )); lse)); _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback);
if (_routeStack.isNotEmpty && _routeStack.last.settings.name == key) { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(false)); } } void unsubscribe(String key) { _subscribers.remove(key); } void _emitLifecycleEvent(Route<dynamic>? route, LifecycleEvent event) { final key = route?.settings.name; if (key == null) { return; } final subscribers = _subscribers[key]; if (subscribers == null) { return; } for (final subscriber in subscribers) { subscriber.call(event); } } }

% 155 @override void didPop(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.remove(route);
_emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } @override void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) { _routeStack.add(route); _emitLifecycleEvent(previousRoute, const LifecycleEventPaused(false)); _emitLifecycleEvent(route, const LifecycleEventResumed(false)); } @override void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { if (_routeStack.last == route) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } _routeStack.remove(route); } } void fin sub if _ } } void _su } void fin if r } fin if r } for

% 158 true)); rue)); @override void didReplace({Route<dynamic>? newRoute, Route<dynamic>? oldRoute})
{ final index = _routeStack.indexWhere((element) => element == oldRoute); if (_routeStack.last == oldRoute) { _emitLifecycleEvent(oldRoute, const LifecycleEventPaused(false)); } _routeStack.remove(oldRoute); if (index >= 0 && newRoute != null) { _routeStack.insert(index, newRoute); } if (_routeStack.last == newRoute) { _emitLifecycleEvent(newRoute, const LifecycleEventResumed(false)); } } void dispose() { _appLifecycleListener.dispose(); _subscribers.clear(); } void subscribe(String key, LifecycleObserverCallback callback) { final Set<LifecycleObserverCallback> subscribers = _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback);

{ final index = _routeStack.indexWhere((element) => element == oldRoute); if (_routeStack.last == oldRoute) { _emitLifecycleEvent(oldRoute, const LifecycleEventPaused(false)); } _routeStack.remove(oldRoute); if (index >= 0 && newRoute != null) { _routeStack.insert(index, newRoute); } if (_routeStack.last == newRoute) { _emitLifecycleEvent(newRoute, const LifecycleEventResumed(false)); } } void dispose() { _appLifecycleListener.dispose(); _subscribers.clear(); } void subscribe(String key, LifecycleObserverCallback callback) { final Set<LifecycleObserverCallback> subscribers = _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback); Page1 Page2 Page3 Page1 Page4 Page3 Page1 Page2 Page3 Page1 Page2 Page4

{ final index = _routeStack.indexWhere((element) => element == oldRoute); if (_routeStack.last == oldRoute) { _emitLifecycleEvent(oldRoute, const LifecycleEventPaused(false)); } _routeStack.remove(oldRoute); if (index >= 0 && newRoute != null) { _routeStack.insert(index, newRoute); } if (_routeStack.last == newRoute) { _emitLifecycleEvent(newRoute, const LifecycleEventResumed(false)); } } void dispose() { _appLifecycleListener.dispose(); _subscribers.clear(); } void subscribe(String key, LifecycleObserverCallback callback) { final Set<LifecycleObserverCallback> subscribers = _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback);

% 161 ; if (_routeStack.last == newRoute) { _emitLifecycleEvent(newRoute, const
LifecycleEventResumed(false)); } } void dispose() { _appLifecycleListener.dispose(); _subscribers.clear(); } void subscribe(String key, LifecycleObserverCallback callback) { final Set<LifecycleObserverCallback> subscribers = _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback); if (_routeStack.isNotEmpty && _routeStack.last.settings.name == key) { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(false)); } } void unsubscribe(String key) { _subscribers.remove(key); } void _emitLifecycleEvent(Route<dynamic>? route, LifecycleEvent event) { final key = route?.settings.name; if (key == null) {

LifecycleEventResumed(false)); } } void dispose() { _appLifecycleListener.dispose(); _subscribers.clear(); } void subscribe(String key, LifecycleObserverCallback callback) { final Set<LifecycleObserverCallback> subscribers = _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback); if (_routeStack.isNotEmpty && _routeStack.last.settings.name == key) { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(false)); } } void unsubscribe(String key) { _subscribers.remove(key); } void _emitLifecycleEvent(Route<dynamic>? route, LifecycleEvent event) { final key = route?.settings.name; if (key == null) {

LifecycleEventResumed(false)); } } void dispose() { _appLifecycleListener.dispose(); _subscribers.clear(); } void subscribe( ɹ String key, LifecycleObserverCallback callback, { bool notifyImmediately = true, }) { final Set<LifecycleObserverCallback> subscribers = _subscribers.putIfAbsent(key, () => {}); subscribers.add(callback); if (notifyImmediately && _routeStack.isNotEmpty && _routeStack.last.settings.name == key) { _emitLifecycleEvent(_routeStack.last, const LifecycleEventResumed(false)); } } void unsubscribe(String key) { _subscribers.remove(key); すぐに通知されてしまうので、適宜フラグで送らないようにするのも良い

% 164 final goRouter = GoRouter( initialLocation: '/', observers: [
appLifecycleObserver, ], routes: [ GoRoute( path: '/', pageBuilder: (context, state) { return MaterialPage( key: state.pageKey, name: '/', child: const MyHomePage(), ); }, ), GoRoute( path: '/page1', pageBuilder: (context, state) { return MaterialPage( key: state.pageKey, name: 'page1', child: const Page1(), ); }, ), GoRoute( path: '/page2', pageBuilder: (context, state) { return MaterialPage( key: state.pageKey, name: 'page2', child: const Page2(), ); }, ), ], ); 利用側

% 165 final goRouter = GoRouter( initialLocation: '/', observers: [
appLifecycleObserver, ], routes: [ GoRoute( path: '/', pageBuilder: (context, state) { return MaterialPage( key: state.pageKey, name: '/', child: const MyHomePage(), ); }, ), GoRoute( path: '/page1', pageBuilder: (context, state) { return MaterialPage( key: state.pageKey, name: 'page1', child: const Page1(), ); }, ), GoRoute( path: '/page2', pageBuilder: (context, state) { return MaterialPage( key: state.pageKey, name: 'page2', child: const Page2(), ); }, ), ], ); 利用側 MaterialPage.nameにnameをセット

% 166 利用側 class _PageState extends State<Page> { bool _initialized
= false; @override void didChangeDependencies() { super.didChangeDependencies(); if(!_initialized) { appLifecycleObserver.subscribe('pageName', (event) { switch (event) { case LifecycleEventResumed(): print('onResume: ${event.isSystemEvent}'); case LifecycleEventPaused(): print('onPause: ${event.isSystemEvent}'); } }); _initialized = true; } } @override Widget build(BuildContext context) { return Container(); } }

= false; @override void didChangeDependencies() { super.didChangeDependencies(); if(!_initialized) { appLifecycleObserver.subscribe('pageName', (event) { switch (event) { case LifecycleEventResumed(): print('onResume: ${event.isSystemEvent}'); case LifecycleEventPaused(): print('onPause: ${event.isSystemEvent}'); } }); _initialized = true; } } @override Widget build(BuildContext context) { return Container(); } }

= false; @override void initState() { super.initState(); if(!_initialized) { appLifecycleObserver.subscribe('pageName', (event) { switch (event) { case LifecycleEventResumed(): print('onResume: ${event.isSystemEvent}'); case LifecycleEventPaused(): print('onPause: ${event.isSystemEvent}'); } }); _initialized = true; } } @override Widget build(BuildContext context) { return Container(); } } Context不要なのでinitStateでも呼べる

% おまけ 169

% 170 Riverpodで使うなら

% 171 @Riverpod(keepAlive: true) AppLifecycleObserver appLifecycleObserver( AppLifecycleObserverRef ref, ) =>
AppLifecycleObserver();

% 172 @riverpod Stream<LifecycleEvent> appLifecycleStream( AppLifecycleStreamRef ref, String key, )
async* { StreamController<LifecycleEvent> eventController = StreamController(); final provider = ref.watch(appLifecycleObserverProvider); provider.subscribe(key, (LifecycleEvent event) { eventController.add(event); }); ref.onDispose(() { provider.unsubscribe(key); }); yield* eventController.stream; }

% Stream<LifecycleEvent> appLifecycleStream( AppLifecycleStreamRef ref, String key, ) async* {
StreamController<LifecycleEvent> eventController = StreamControll final provider = ref.watch(appLifecycleObserverProvider); provider.subscribe(key, (LifecycleEvent event) { eventController.add(event); }); ref.onDispose(() { provider.unsubscribe(key); }); yield* eventController.stream; } 173 appLifecycleObserverは内部で参照

% 174 Stream<LifecycleEvent> appLifecycleStream( AppLifecycleStreamRef ref, String key, ) async*
{ StreamController<LifecycleEvent> eventController = StreamControll final provider = ref.watch(appLifecycleObserverProvider); provider.subscribe(key, (LifecycleEvent event) { eventController.add(event); }); ref.onDispose(() { provider.unsubscribe(key); }); yield* eventController.stream; } 渡されたKey(Route name)でsubscribe

% 175 Stream<LifecycleEvent> appLifecycleStream( AppLifecycleStreamRef ref, String key, ) async*
{ StreamController<LifecycleEvent> eventController = StreamControll final provider = ref.watch(appLifecycleObserverProvider); provider.subscribe(key, (LifecycleEvent event) { eventController.add(event); }); ref.onDispose(() { provider.unsubscribe(key); }); yield* eventController.stream; } Disposeで自動unsubscribe

% 176 利用側 final event = ref.watch(appLifecycleStreamProvider('page1')); switch(event) { case
AsyncData(:final value): print(value); }

% 177 goRouter.routerDelegate.currentConfiguration.routes; GoRouter内で管理しているNavigation historyを取得できる

% 178 @override void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { if
(_routeStack.last == route) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } _routeStack.remove(route); } @override void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { final top = goRouter.routerDelegate.currentConfiguration.routes.lastOrNull; if (top != null && (top as GoRoute).name == route.settings.name) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } } 自分で管理 GoRouterを参照

(_routeStack.last == route) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } _routeStack.remove(route); } @override void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { final top = goRouter.routerDelegate.currentConfiguration.routes.lastOrNull; if (top != null && (top as GoRoute).name == route.settings.name) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } } 自分で管理 GoRouterを参照

(_routeStack.last == route) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } _routeStack.remove(route); } @override void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { final top = goRouter.routerDelegate.currentConfiguration.routes.lastOrNull; if (top != null && (top as GoRoute).name == route.settings.name) { _emitLifecycleEvent(route, const LifecycleEventPaused(false)); _emitLifecycleEvent(previousRoute, const LifecycleEventResumed(false)); } } 自分で管理 GoRouterを参照 Master of Flutter lifecycle Introduction Widget lifecycle App lifecycle Navigation & Routing Handling Flutter lifecycle Summary

% X @override void didRemove(Route<dynamic> route, Route<dynamic>? previousRoute) { if

% • Widget, App, Navigationそれぞれのライフサイクルを学んだ • Flutter3.13.0からイベントの発火タイミングが変わったので注意が必要 • FlutterはEverything is
a widgetになっているため、画面遷移のライフサイクルイベントはNavigationを考慮する必要がある • それぞれを組み合わせて初めてFlutterのライフサイクルにあった処理ができる • 今日のサンプルコード https://github.com/AAkira/ fl utter_lifecycle_example 182 Summary

Thank you! @_a_akira We are hiring! https://jobs.m3.com/engineer/

Master of Flutter lifecycle / Flutter Kaigi 2023

Master of Flutter lifecycle / Flutter Kaigi 2023

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